Refrigeration



Aug. 4, 1942.

Filed April 24, 1959 C. 3. COONS ETAL `REFRIGERATION 56* /lG .40 E RN x l L l' Igll ffggg ff ggg 'TA /e ====iii I B L Y INVEN'roR Z/ i Cuffia 600176" BY S'anley Cumm lys ATTORNEY Aug-4 C. C. COONS ETAL i REFRIGERATION Filed April 24, 1959 I z'sneets-sheet-z INVENTOR FWZ y cams c. C0 0115 Stahl@ l?. Cummzn 512s ATTORNEY Patented Aug. 4, 1942 c REFRIGERA'IION Curtis C. Coons, North Canton, and Stanley R. Cummings, Canton, Ohio, assignors to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application spin 24, 1939, serial No. 269,616

` 16 claims. (crea-119.5)

This invention relates to the art of refrigeration and more particularly to' a novel-absorption refrigerating system which is characterized in that it possesses great flexibility, economy and emciency of operation.

Previously the designs` of refrigerating systems of the type in which an inert gas is utilized have been seriously hampered by limitations, inherent in such systems, upon the relative sizes and locations of various portions of the absorption solution circuit. In previous designs it has been necessaryto make a rather unsatisfactory compromise between the space limitations. imposed by acceptable sizes ofV domestic refrigerating cabinets, the inherent limits'of the system on the i height through which the system pressure differentials will serve to elevate the absorption solution and upon the inherent limitations and functionally correct sizes of various portions of the apparatus. Heretofore it 'has been necessary either to provide an insufficient elevation between dierent portions of the absorber and to place the absorber in a cramped position in the cabinet or to construct the boiler-analyzer system of an excessive size and particularly of an excessive height in order to provide adequate circulation of the absorption solution. Moreover these functionally unsatisfactory design expedients have resulted in the provision of very large cumbersome boiler-analyzer systems which extend to a height totally unnecessary for efficient operation and which, moreover, require an unnecessarily large charge of the solution to be contained therein, a charge which is unjustified from the viewpoint of 'functional efiiciency. These departures from functionally correct design have brought in their train diiilculties due to great pressure differentials between various portions of the apparatus, and to excessive variations in the liquid levels which produce consequent excessive variations in the rate of solution circulation which in turn seriously affects the absorbing and evaporating elciency of the system as a whole.

Accordingly, it is a principal object of the present invention to provide an absorption refrigerating system which is functionally correct and which will achieve desirable high lifting heights within the apparatus without creating excessive pressure differentials therein, requiring excessive size of various portions of the apparatus and without necessitating that the charge be larger than that indicated fox` optimum functional eillciency. f

It is one object of the present invention to pro- I vide an absorption refrigerating system of the inert gas type in which the absorption solution is elevated from the boiler in the absorber in a plurality of easy stages, all of which are operated by. a pressure differentiall withinV the system which is inadequatev to elevate the solution through the desired height in a single step.

n is S6111 another object o f the invention toprovide an absorption refrigerating system of the inert gas type in which the rate of absorption solution circulation is substantially unaffected by minor system disturbances, such as nuctuations in the liquid level and variations in pressure differential whereby to provide a very constant reliable rate of circulation of the absorption solution.

It is a still further object of the present invention to provide an absorption refrigerating system of the type utilizing an inert gas in which the inherent flexibility of the system permits the same to be incorporated in a domestic refrigerating cabinet with a maximum of space economy and to permitthe mechanism containing portions of the apparatus to be decreased in size as compared with previous constructions.

It is a further object of the present invention to provide an absorption refrigerating system of the type utilizing an inert gas in which the absorber may be positioned vertically in a rear aircooling flue of the apparatus without interfering with the functional design of other portions of the kapparatus and without imposing a burdensome circulating load on other portions 0f the apparatus and without requiring that excessive pressure differentials be maintained in different portions of the system.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawings in which:

Figure 1 is a diagrammatic representation of an absorption refrigerating system embodying the present invention, and

Figure 2 is a partial side elevational sectional lview illustrating the arrangement of the parts illustrated in Figure l within a cabinet.

Referring now to the drawings in detail and particularly to Figure 1 thereof, there is disclosed a three-fluid absorption refrigerating system comprising a boiler B, an analyzer D, an aircooled rectifier R, a tubular air-cooled condenser C, an evaporator E, a gas heat exchanger G, a tubular air-cooled absorber A, a solution reservoir S, a liquid heat exchanger L, and a circulating fan F which is driven by an electrical motor M. These elements are suitably interconnected by various conduits to form a plurality of gas and liquid circuits constituting a complete refrigerating system to which reference will be made in more detail hereinafter.

The above described apparatus will be charged with a suitable refrigerant, such as ammonia, an absorbent therefor, such as water, and a pressure equalizing gas which is inert with respect to the refrigerant and the absorbent, preferably a dense inert gas like nitrogen.

The boiler B may be heated in any suitable manner as .by a combustible fuel burner or an electrical cartridge heater.

The application of heat to the boiler B generates refrigerant vapor from the solution normally therein contained. The vapors so generated passI means of a conduit I5, the liquid heat exchanger L, and a finned air-cooled conduit I6 which also serves as a solution pre-cooler. As shown, the absorber A comprises two groups of parallel downwardly inclined tubes I8 and I9 which are positioned in staggered relationship in parallel vertical planes and are-serial1y connected together. The arrangement is such that the lower end of any particular one of the conduits in the groups I8 and I9 is connected to the upper end of the next lowest conduit in the other group, thereby to provide a continuous path of flow for the absorption solution and the inert gas. Each individual conduit is individually nned to provide for air-cooling, though a continuous fin may be applied to each group of tubes I8 and I9 if desired. 'Ihe absorber may be formed from a continuous tube bent into the required shape or from a plurality of preformed tube sections suitably secured together as by welding. It is apparent that the upper end of the vertical absorber is at an elevation very appreciably above the elevation of the solution reservoir S and that the lower end ofthe absorber is at an elevation slightly above the upper portion of the analyzer It has been proposed previously to elevate the absorption solution from the solution reservoir into the upper end of the absorber by providing a gas lift pump therebetween. '-Ihis construction operates very satisfactorily in many types of systems; however, there is a definite limit to the height through which the liquid can be elevated by these meansboth from the viewpoint of the available pressure di'erential in the inert gas circuit for operating the pump and also because the sensitivity of the circulating mechanism to minor lsystem disturbances, such as minor variations in pressure diilerentials and variations in liquid levels which -tend to limit the practical height through which the solution may be elevated by the gas lift pump. Furthermore, considerations of the size of the circulating fan, the cost of the apparatus, the design of the gas heat exchanger, evaporator and absorber all tend to nx a fairly rigid value for the gas pressure differential which should be developed across the circulating fan. all `of which in turn impose rather rigid limitations upon the design and arrangement of the absorber and of the other parts of the solution circuit.

In accordance with the present invention; however, the lean solution which is supplied to the reservoir B is conveyed therefrom by means of a conduit 2| intov the bight portion of a ll-shaped twin gas lift pump 22 which discharges into a collection and scparation vessel 22. Pumping gas is supplied to each of the legs of the pump 22 through an inverted U-shaped conduit 25 which -connects to the legs of the pump 22 below the C. Coons and Rudolph B. Nelson, Serial No. 169,-

986, illed October 20, 1937. Patent N0.`2,240,176. A twin gas lift pump is one having one or more elevating conduits which are in unobstructed communication with a source of gas under pressure at a level below the liquid level prevailing in the elevating conduit under static conditions, are in open and unobstructed communication with a source of the liquid to be pumped, and are in unobstructed communication with a conduit or chamber adapted to house an oscillating piston or body of liquid. As is illustrated in this application, the lowest of the two twin-gas lift pumps shown in Figure l comprises an upstanding U- shaped conduit which includes a pair of elevating conduits-the legs of the U-designated by the reference character 22 and an inverted U-shaped conduit 25 which communicates, with a source of gas under pressure and with each of the elevating conduits 22. Communication with a -source of liquid to be pumped is provided by the conduit 2I opening into the bight portion of the U- shaped pump structure. The oscillating column or chamber is the bight portion of. the U-shaped conduit.

The lean solution which collects in the bottom portion' of the vessel 23 is conveyed therefrom by means of a conduit 30 into the bight portion of a second U-shaped'twin gas lift pump 3| which discharges into a second collection and separation vessel I2. Pumping gas is supplied to the twin pump 3| by means of an inverted U-shaped conduit 34 which connects with the legs of the pump 3| below the liquide level normally therein contained. Gas is supplied to the bight portion of the conduit 34 by means of a conduit 35 whichl communicates with the conduit 21 previously described.

The lean solution supplied 'to the vessel 22 is drained therefrom by means of a conduit l! into the suction conduit .21 of the circulating fan which connects directly to the top portion of the absorber A. l

'I'he solutionl reservoir S, the separation chamber 23 and the separation chamber 32 are all vented to the conduit 21 by means of conduits 2l; I9 and 40. respectively, which join a conduit Il directly connected to the conduit 31. By reason of this venting system each gas lift pump operates with the maximum available pressure differential found in the system and the pressure differential is substantially constant because the circulating fan F operates at a constant speed.

The gas lift pump 22 has a capacity slightly in excess of the gas lift pump 3| which is designed to elevate the quantity of absorption solution which'should be suppliedto the absorber. The vessel 23 is provided with a return drain I3 which connects to the lean solution supply conduit 2|. The position of the return drain 43 determines the liquid level in the vessel 23 and hence the depth of immersion of the elevating pump 3|, and, due to the fact that the capacity of the pump 22 is greater than that of the pump 3|, this depth of immersion remains constant independently of any variations which may occur in other parts of the system. Consequently, there will be a recirculation of a small 1 quantity of absorption solution through the gas lift pump 22 and the return conduit 43.

The lean solution which is supplied tothe upper portion of the absorber by the conduits 36 and 31 iiows downwardly therethrough by gravity counter to an upwardly iiowing mixture of inert gas and refrigerantvapor. The refrigerant vapor content of the mixture is absorbed by the solution and the heat'of absorption is rescribed heretofore.

jected to cooling air passing across the absorber tubes and the fins mounted thereon.

The strong solution formed in the absorber by the absorption of refrigerant vapor drains into the rich gas-inlet conduit 53 at the lower end of the absorber and is conveyed therefrom into the upper portion of the analyzer D by the conduit 44, the inner pass of the liquid heat exchanger L and the conduit 45.

The refrigerant vapor supplied to the condenser C is liquifled therein by heat exchange with atmospheric air and is discharged from the bottom portion thereof into the bottom portion of the evaporator E through a conduit 66 which includes a U-shaped liquid seal and pressure balancing column forming portion tl. The conduit 46 is also vented by means of the conduit 43 to the rich gas side of the gas heat exchanger G.

In the bottom portion of the evaporatorl E the liquid refrigerant contacts lean gas which is conveyed from the top portion o f the absorber A by way of the conduit 31, the circulating fan F, the conduit 2S, the outer path of the gas heat exchanger G, and a conduit t3. The inert gas sweeps or drags the liquid refrigerant upwardly through the evaporator as the liquid is evaporatdownwardly therethrough in the manner de- The evaporator is provided with a lsafety antiblock drain 56 which is connected between the upper portion of the lowest evaporator conduit and the rich solution return conduit Il. l

Referring now to Figure 2, the manner inwhich the apparatus is enclosed in a refrigerator cabinet will be described. The apparatus includes a cabinet 60 comprising an insulated freezing and storage chamber 3| which overlies a shallow mechanism compartment l2 and is provided with a rear air-cooling flue I3. The evaporator E and the box-cooling conduit Il are mounted within the chamber 3| and the freezing portion of the evaporator E will be enclosed in a suitable casing for housing freezing trays and the like, as illustrated.

The rear wall of the insulated compartment 3| is provided with an opening 66 which receives an insulated panel SIof a size to permit the 'evapora'tor to pass through the opening 36 and to seal that opening. A suitable gasket 33 is provided to prevent air leakage around the margins of the panel Si.

The gas heat exchanger G is partially embedded in the rear insulated vwall of the compartment 6| and in the panel 61.

As is illustrated clearly in Figure 2, the condenser C extends diagonally across the upper portion of the flue 33/and the air-cooled absorber A is vertically mounted in the lower portion thereof with its lower end positioned at an elevation slightly above the elevation of the liquid inlet to the analyzer D. The gas lift pumps 22 'and 3| and their associated conduits and sep-v arating vessels 23 and 32, respectively, are positioned in the extreme rear portion of the mechanism compartment 62 and beneath the lower end ment. and particularly that portion thereof 'dling thereinto to produce useful refrigeration.

As herein illustrated, the evaporator is shown diagrammatically. However, any suitable arrangement and form of evaporator may be utilized. A preferred construction is illustrated and described in the co-pending application of Curtis C. Coons and William H. Kitto, Serial No. 386,395, filed April 2,' 1941. v

After passing through the lower portion of the evaporator E the inert gas and liquid refrigerant are discharged into the upper enlarged diameter finned box-cooling conduit 50 after which the rich gas produced by the evaporation of the liquid refrigerant is conveyed from the Y box-cooling conduit 50 into the rich gas side of the gas heat exchanger G by means of a conduit 52. After passing through the gas heat exchanger the rich' gas is conveyed therefrom to' the bottom portion of the absorber A by means of a conduit 53. The rich gas thenpasses upwardly through the absorber A in counterflow relationship to the absorption solution flowing of the ue 63. For purposes, of clarity in this figure the gas lift pumps are shown as being of the single lift rather than of the twin lift type, though it should be understoodthat the twin lift type is to be preferred even though either type mav be utilized without departing from the spirit of the present invention.

Cooling air may be admitted to the bottom portion of the flue 63 and the mechanism compartment 62 in any desired manner. As illustrated the lower end of the mechanism compartrectly beneath the flue 63, is open to allow cooling air to fiow inwardly thereof and upwardly.

through the flue 33 to remove the heat of absorption, condensation and rectification from the apparatus.

Figure 2 well illustrates the manner in which the present invention allows the mechanism compartment to be made of extremely low height and permits the absorber to extend vertically in the fiue without requiring an excessively large fan,

without requiring an excessively large boileranalyzer and without imposing any pumping load l on the apparatus approaching or above its maxi-'- mum capacity forthat purpose.

In accordance with the present invention there is therefore provided an absorption refrigerating system in which extreme flexibility is provided,

accuracy of absorption solu'ion circulation rate is provided and the position of the absorber relative to the boiler-analyzer maybe selected within a widel range 'of possibilities without imposing any undue loads upon the apparatusrequiring excessive sizes or proportions thereof and without reouiring the use of abnormally large quani tities oi' absorption solution in the charge.

Though the present invention may be practicedv by utilizing single lift pumps in place of twin gas lift pumps 22 and 3l illustrated in Figure 1, the twin lift gas type of pump is to be preferred as it is more eilicient and 'will elevatean absorber, an inert gas circuit including an evaporator and said absorber, said solution circuit including a plurality of serially connected circulating devices positioned at different elevations arranged to convey solution from said boiler to said absorber, one of said-circulating devices having a greater capacity than the circulating device to which it supplies solution, and means for returning to the inlet portion of said one circulating device the excess solution flowing therethrough.

2. Absorption refrigerating apparatus comprising a solution circuit including a boiler and an absorber, an inert gas circuit including an evaporator and said absorber, said solution cir-v cuit including a plurality of serially connected twin gas lift pumps arranged to convey solution from said boiler to said absorber.

3. Absorption refrigerating apparatus comprising a solution circuit including a boiler and an absorber, an inert gas circuit including an evaporator and said absorber, said solution circuit including a plurality of serially connected gas lift pumps arranged to convey solution from said boiler to said absorber, and means for leading a portion of the gas flowing in said inert gasv circuit into said gas lift pumps to operate the same. Y

4. Absorption refrigerating apparatus comprising a solution circuit including a boiler and an absorber, an inert gas circuit including an evaporator and said absorber, and power driven means for propelling the inert gas through said inert gas circuit, said solution circuit including a plurality of serially connected gas lift pumps arranged to convey solution from said boiler to said absorber. Y

5. Absorption refrigerating apparatus comprising a solution circuit including a boiler and anabsorber, an inert gas circuit including an evaporator and said absorber, a power driven circulator in said inert gas circuit, said absorber comprising a sinuous ilnned' conduit having one end connected to drain solution into said boiler, means for elevating absorption solution from said boiler into said absorber comprising a pai.l of twin gas lift pumps, one of said pumps being connected to receive absorption solution from said boiler and to discharge the same into a separation chamber which is connected to the inlet portion of the other of said pumps, the other ,of said pumps being arranged to discharge into from the discharge side 0i said circulator to said twin gas lift pumps, and means for subjecting said absorber, means for supplying pumping gas cuit including a plurality of serially connected gas lift pumps arranged to convey solution from said boiler to said absorber, reservoirs situated in the supply line of each of said pumps, and means for venting said reservoirs and the discharge sides of said gas lift pumps to the inert gas circuit.

7. Absorption refrigerating apparatus comprising a solution circuit including a .boiler and an absorber, an inert gas circuit including an evaporator and said absorber, power driven means for circulatingy the pressure equalizing medium through said pressure equalizing medium circuit, said absorber being positioned relatively to said boiler at such an elevation that the pressure differential developed by said circulating means is inadequate to elevate solution directly from said boiler to said absorber and means operated by such pressure differential for elevating solution from said boiler into said absorber comprising a plurality of serially connected pressure equalizing medium operated pumps each of which is arranged to elevate the absorption solution through a height within the elevating limits of such pressure diierential.

8. Refrigeratlng apparatus including a cabinet having an insulated refrigerating compartment, a shallow chamber underlying said compartment, an air duct extending upwardly alongside said compartment, an evaporator in said compartment, an upstanding tubular air-cooled absorber in said duct, a boiler in said chamber. a plurality of serially connected gas lift pumps arranged to elevate absorption solution from said boiler into said absorber, said gas lift pumps being positioned at diierent elevations, the lowest of said gas lift pumps being positioned in said chamber to receive absorption solution by gravity from said boiler and the highest of said gas lift pumps extending upwardly in said duct and arranged to discharge absorption solution into the upper portion of said absorber, a condenser in the upper portion of said duct connected to receive refrigerant vapor from said boiler and to supply refrigerant liquid to said evaporator, and means for conveying refrigerant vapor from said evaporator to said absorber, and means providing for circulation of an inert gas between said evaporator and said absorber and for supplying pumping gas to said gas lift pumps.

9. Refrigerating apparatus including a cabinet having an insulated refrigerating compartment, a shallow chamber underlying said compartment, an absorption refrigerating apparatus of the type utilizing an inert gas associated with said cabinet including a boiler in said chamber, a vertical air-cooled absorber in said duct extending to a level materially above the top wall of said chamber, a pair of serially connected gas lift pumps arranged to elevate absorption solution from said boiler into said absorber, power driven means for propelling inert gas through a. circuit including said absorber and means for leading gas from said circuit into said pumps to operate the same.

` 10. Refrigerating apparatus comprising a cabinet including an insulated storage chamber having an air cooled machinery compartment associated therewith, an absorption refrigerating I j t machine associated with said cabinet comprising an inert gas circuit including an evaporator positioned in said chamberand an upright tubuwhich is within the elevating limits of such pressure differential.

1er au cooled absorber in saideompartment, a.` l

solution circuit including a generator and said absorber, an air-cooled condenser in said compartment connected vto receive refrigerant vapor from saldgenerator and t supply refrigerant 13. Refrigerating apparatus comprising a cabinet including an insulated storage chamber having an airv cooled machinery compartment associated therewith, an absorption refrigerating machine associated with said cabinet compris-v ing an inert gas circuit including an evaporator liquid to said evaporator, and a plurality of seri- Y highest of said circulators being arranged to receive absorption solution elevated from said generator and to lift such. absorption solution int the upper part of said upright absorber. t i 1l. Refrigerating apparatus comprising a cabinetinciuding an insulated storage chamber having'an air cooled machinery compartment associated therewith, an absorption refrigerating machine associated with'said cabinet comprising an inert gas circuit including an evaporator positioned in said chamber and an upright tubular air cooled absorber in said compartment, a

power driven circulator in said inert'gas circuit,

a solution circuit including a generator and said absorber, an air cooled condenser in said compartment connected to receive refrigerant vapor from said generator and to supply refrigerant liquid to said evaporator, said absorber being positioned relatively to said boiler at such an ele- ,vation that the pressure dierential developed by said circulator is inadequate to elevate solution directly from said generator to saidabsorber, and a plurality or vertically spaced serially connected gas lift pumps included in said solution circuit for elevating absorption solution into said absorber, each of said pumps being arranged to elevate the absorption solution through a height which is within the elevating limits of such pressure diderential.

12. Refrigerating apparatus comprising a cabinet including an insulated storage chamber having an air cooled machinery compartment associated therewith, an absorption refrlgerating machine associated with said cabinet comprising an inert gas circuit including an evaporator positioned in said chamber and an upright tubular air cooled absorber in said compartment, a power driven circulator in said inert gas circuit, a soin-1 -tion circuit including a generator and said absorber, .an air cooled condenser in said compartment connected to receive refrigerant vapor from said generator and to supply refrigerant liquid to said evaporator, said absorber comprising a sinuous tube bent to form a. plurality of alter` nately oppositely inclined serially connected conduits, the conduits of like inclination lying in a common plane spaced from the conduits'of opposite inclination and heat rejecting :uns attached to said conduits. said absorber being positioned relatively to said boiler at such an elevation that the pressure diderential developed by said circulator is inadequate to elevate solution directly from said generator to said absorber, and a plurality of vertically spaced serially connected gas lift pumps included in said solution' circuit for elevating absorption solution into said absorber. each of said pumps being arranged to elevate the absorption solution through positioned in said chamber and an upright tubular air cooled absorber in said compartment, a power driven circulator in said inert gas circuit. a solution circuit including a generator and said absorber, an air cooled condenser in said compartment connected to receive refrigerant vapor from said' generator and to supply refrigerant liquid to said evaporator. said absorber being positioned relatively to said boiler at such an elevation that the pressure differential developed by said circulator is inadequate to elevate solution directly from said generator to said abv sorber, a plurality of vertically spaced serially connected twin gas lift pumps included in said solution circuit iol-,elevating absorption solution into said absorber; each of said pumps being arranged to elevate the absorptionv solution through a'height which is. within the .elevating limits of -fsuchpressure differential, and means for leading gas from said inert gas circuit into said pumps for operating the same.

14. In combination, a cabinet having a food storage compartment and an apparatus compartment including avertically positioned air flue,

an evaporator insald storage compartment, a

vertically positioned absorber in said flue, a

closed inert gas circuit between the evaporator I and absorber, a solution circuit including said absorber having a solutionlevel below the top of said absorber, a circulator unit in said gas circuit for circulating the gas in its circuit and for raising the pressure therein above that normally prevailing in the evaporator and means for utilizing a portion vof the gas at its raised pressure for vraising the solution to the top oi said absorber.

15. In combination, a cabinet having a food storage compartment and an apparatuscompartment including a vertically 1 positioned air flue, an evaporator in said food storage compartment, a condenser and a vertically positioned absorber in said flue, said evaporator being positloned above the bottom of said condenser, a

closed inert gas circuit between the evaporator` and absorber, a circulator unit in said gas circuit for raising the pressure of the gas and for circulating the gas in its circuit, means for'utilizing a portion of said gas at said raised pressure for raising solution to the top of said absorber, and means for leading condensed refrigerant from said condenser to the bottom of said evaporator, said evaporator and said gas circuit being so constructed and arranged that the remainer of said gas at its raised pressure will raise the liquid refrigerant upwardly through the evaporator.

16. In combination, a cabinet having a food storage chamber vand an apparatus compartment including a vertically extending air duct,- an evaporator arranged to refrigeratesaid food storage chamber, a vertically extending absorber in said duct, a closed inertgas circuit 'including said evaporator and said absorber, a solution circuit including said absorber and a generator and having a liquid level below the upper portion of said absorber, a circulator in said gas circuit for a height 78 6 l assume I portion of saidevaporator and connected to receive refrigerant vapor from said generator and to supply liquid refrigerant to the lower portion I of said evaporator. las lift pump means arranged to elevate absorption solution from d generator to the upper portion ot'aaid absorber, and

meansi'orsupplyingaportionoltheinertgasatthe raised pressure t@k said gas lift pump means velocity and pressure to raise liquid refrigerant A upwardly through said evaporator.

CURTIS C. COONB. BTANIEY R. CUMMINGB. 

